This invention relates generally to turbines, such as are used for power generation, and, more specifically, to methods, systems and apparatus for cleaning turbines.
A turbine, such as is used for power generation, may use a variety of fuels, such as natural or synthetic gas, and atomized liquid fuels of various weights and viscosities. No matter what fuel is used, the blades and other structures in the turbine are subject over time to the build up of deposits of various residues that are byproducts of the combustion process. Deposit build up results in loss of turbine efficiency and potential degradation of turbine components.
Efforts to address the build up of combustion by-product deposits include washing the turbine at periodic intervals. Known washing methods involve the spraying of water and/or cleaning agents axially into the bellmouth of the turbine through predetermined nozzle arrangements, while the turbine is rotated at a relatively slow speed. However, such known methods typically result in effective cleaning only to about the seventh stage of the compressor portion of the turbine. Often, the water and/or cleaning agents are degraded or vaporized by the time the latter stages are reached. Furthermore, such known techniques can result in debris or deposit build up material simply migrating to the higher (downstream) stages of the turbine. In addition, nozzle plugging can also reduce cleaning effectiveness. Also, dedicated nozzles can become plugged, leading to undesired variations in spray pattern and loss of efficiency.
Other known methods for cleaning turbines have included increasing the duration and/or frequency of the washes, increasing the ratio of cleaning agent to water, changing the type of cleaning agent used, use of foam-based cleaning agents (which migrate more easily into tight areas and the latter stages of turbines), and/or implementing a policy of periodic manual cleaning.